Improvement in telegraph apparatus



Duplex Telegraph.

Nou 78,548. Pat'ented .lune 2, 1868E Fvg cadr 52,5503/ N4 PETERS.Phnxouxhogmpher. wamngm". uc,

UNITED STATES PATENT OEEICE;

JOSEPH B. STEARNS, OF BOSTON, MASSACHUSETTS.

Specification'forming part of Letters Patent No. 78,548, dated June 2,1868.

Beit known that I, JosEPH B. STEAnNs, of Boston, in the county ofSuffolk and State of Massachusetts, have invented a new and usefulImprovement in Electric Telegraphs, of which the following is a full,clear, and eX- act description, reference being had to the accompanyingdrawings making a part of thisspeciication,andrepresentingthevariousparts of a telegraphic apparatusfor carrying out my invention.

Figure l represents a general view of the apparatus. Figs. 2, 3, and 4are modifications of portions of the same.

The object of my invention is to provide an efficient means fortransmitting two messages simultaneously over a single wire in oppositedirections; and the invention consists in so constructing and arrangingthe key or other circuit-breaker and the electro-magnets that thecurrent from the battery at what we will for convenience call the homestation will, on being called into action, be divided, one portionpassing through. an electro-magnet, which in the drawing is marked E, tothe line, and thence to the distant station, the other portion passingthrough a similar electro-magnet, marked E in the drawing, to andthrough a rheostat, R, and thence to the ground. The electro-magnets areso placed in relationto the armature that their effects upon it areequal and opposite to each other, and consequently the armature isunmoved, While at the same time a current from the batteryat vthedistant station can` pass over the line L through magnet E only, thenceto lever l of the key or circuit-breaker, and thence to the groundthrough wire a, rheostat It', and wire g, if the key D is in contactwith its back stop p, or by lever l and wire et to the main battery M B,and thence by wire g to the ground, it' key D is in contact with itsfront stop o. In either position of the key the current from the distantstation nds a passage to the ground, and charges magnet E, moving thearmature h. It is obvious that this armature may, by its movement, closea local circuit, and operate a second sounder for the accommodation ofthe receiving operator. Itheostat R is so adjusted that its resistanceis about equal to that of the line to the distant station, and theapparatus there. It is evident that when the current from the distantstation arrives at c it finds two channels open to it-one by wire e,through magnet E and rheostat It, to the ground, the other by wire bthrough lever l', and to the ground either by lever Z, wire a., batteryM B, and wire g, or through It and wire g, according to the position ofthe key or lever D of the circuitbreaker. Now, as the resistance offeredto the current by the first-mentioned channel is eX- ceedingly great ascompared to that offered by the other channel, the proportion ot' thecurrent that will be deiected and' pass through this channel willbe'exceedingly small compared to that passing through the other and moredirect channel, and thus the influence of magnet E upon the armature Itwill not be appreciable.

The object of rheostat It is, by its proper adjustment, to cause thesame amount ot' electricity from the battery at the home station to passthrough magnet E' as through magnet E, and thus causing the attractionot' E to be equal to that of E upon the armature. The object of thesmall rheostat-R is, by its` proper adjustment, to offer the same ornearly the same resistance to the current from the distant station as isoffered by the batteryM B, thus preserving the resistance for thecurrent A from the distant station alwaysthe samea result of great importance, and, as Ibelieve, never before accomplished. It also serves toprevent sparks at the points of contact in the key or circuit-breaker.Resistance-coils, for the purpose of preventing the sparks at the pointsof contact, may be inserted in the wire between the key and the ground,and between th'e key yand the battery, thus leaving nothing for therheostat It to do but to equalize the resistance, as already explained.

The key or circuit-breaker is so constructed that it closes one circuitor channel for the current from the distant station before or at thesame time that it opens the other. In practice, I prefer to make the keyor circuitbreaker in the form of a common sounder, the lever of whichsupplies the place of the lever of a common key, and, being furnishedwith an armature, can be manipulated by an electro-magnet, localbattery, and common key, as shown in the drawings.- The advantage ofthis arrangement isthat the sending operator hears his own writing, andcan thus better guard against mistakes. Another advantage is that thewriting is made with more firmness and regularity than -by thefingerkey. -Y

Referring to the drawings, K represents a telegraph-key of the ordinaryconstruction, and with which the sending operator works, and is used, inconnection with local battery L B, electro-magnet S, and wires la k k,to manipulate the mainyline key D, which has two levers, l and l. From la wire, a, extends to one end, say the positive, of the battery M B,from the opposite end of which the wire g extends to the ground g 1'.From lever l a wire, b, leads to point c, where it connects with wire d,leading to magnet E, and thence to the line L, and with wire e leadingto magnet Ef, and thence throughrheostat R to the ground gr. m is astop, against which le- Ver Z rests when the lever D is in contact withits back stop n'. From stop m a wire exf tends to rheostatlt, and thenceto the ground g r. The apparatus at the distant station is precisely thesame as at the home station, with the exception that the negative endofthe battery is connected with lever l, and the positive end with theground.

The operation is as follows: The key K being depressed, and brought incontact with point r, a current is established through wire 7c, localbattery L B, wire k', electro-magnet S, and wire k, completing thecircuit, and attractin g the armature t and lever D, or main-V line key,lever Z of which breaks'the connection between Z and m, andestablishes-a connection between l and l. The current from the battery MB now passes through wire a, levers l and l', wire b, to point c, whereit divides, one portion passing through magnet E to the line, and thenceto the distant station, and through the apparatus there into the ground,and thence through the ground back to battery M B, completing thecircuit, and

charging magnet E, which tends to attract armature h. The other portionof the current passes from point c, through wire e, magnet E', rheostatR, and thence to the ground, and back to the battery M B, completing thecircuit, and charging magnet E', which also tends to attract armature hin the other direction and with equal force, the result of which is thatthe two forces counteract each other, and produce no motion of thearmature.

It', now, the key at the distant station is depressed, and the currentof the battery there is thus thrown upon the line, this `new currentwill pass over the line to the home-station, through magnet E, to pointc, where it divides, one portion passing through magnet E' and rheostatR to the ground, the other portion passing by wire b, levers L and l',wire a, to battery M B, and thence to the ground.

The proportion of the current that will be conveyed by the differentchannels will be in inverse proportion to the resistance of each, and,as the first-mentioned course contains many times as much resistance asthe latter,

the amount of current passing through magnet E will not be appreciable,and magnet 'E will act upon armature h as though magnet l E were notpresent. It' the key at the home station is not depressed at the timevthe current is thrown upon the line at the distant station, then thatcurrent passes over the line, and through magnet E, as before, and bywires d and b, lever l', rest m, wire n, rheostat R', wire gf, to theground, and back to the battery from whence it started, acting upon themagnet E and armature h, as in the former case.

The advantage of this method over all others heretofore devised consistsin the facility with which it can be adjusted, for while in othermethods the adjustment of the forces acting upon the armature dependsalmost wholly upon the proper regulating of the resistance ot' therheostat, which in practice is found to be troublesome, in this methodthere are several modes of adjustment, and such as are more generallyand readily understood by those who are commonly called upon to man agesuch instruments, such as varying the distance of one or the other orboth of the magnets from the armature, so that the exact adjustment ofrheostat Itis of little moment, since, it' it contains several times asmuch resistance at the line, thus allowing' much less than half of thecurrent from battery M B to pass through magnet E', the operator has butto move magnet E nearer armature h to enable its feebler magnetism tobalance the stronger magnet E. This adjustment is more easily understoodand effected by operators than that by rheostat, and is therefore morepractical. l

Another and greater advantage that this method possesses over others is,that the current from either battery meets with exactly the sameresistance, whatever may be the position of the key at the opposite endof the line. This is of great importance.

As a modification of the relay-magnet, the two magnets may be placed oneabove the other, as in Fig. 2, the armaturepost carrying two armatures,with the fulcrum between them; or four magnets may be used, as in Fig.3, with armatures arranged as before, but with magnets on each side ofboth. When arranged in the latter manner, magnets l and 3 may beconnected, so as to actin concert upon the two armatures, and magnets 2and 4 so connected as to oppose the action of l and 2.

I am aware that it is not new to make a key that shall close one circuitbefore or at the same time that it opens another. I am also aware thatit is not new to place two or more electro-magnets in such position thatthey shall act upon the same armature-lever; but I believe it to be newto so place two or more'electro-magnets that they shall act upon thesame armature or armatures, upon the same post, in opposite directions,and with equal force, for' the purpose of .sending two messagessimultaneously over the same wire, in opposite directions.

l also believe it to be new to so arrange the several parts of anapparatus, for the purpose aforesaid, that the resistance to the currentof the battery or batteries shall be at all times the same.

I also believe it to be new to so arrange and construct the severalparts of an apparatus, for the purpose aforesaid, that the neradjustments to prevent the movement of the armature may be ei'ected bythe movement of the electro-magnet toward or from the armature, andwithout changing the resistance of the rheostat.

I also believe it to be new to combine a key that shall close onecircuit before or at the saine time that it opens another with a relaycomposed of two or more electro-magnets operating upon the same armatureor armatures, upon the same post, and in opposite directions, and forthe purpose described.

I therefore claim as my invention, and desire to secure by LettersPatentl. The combination of a relay, consisting of two electro-magnets,so arranged as to act upon the same armature-post, in oppositedirections, with a key that shall close one circuit before or at thesame time that it opens another, when the same are constructed and madeto operate substantially as-described.

2. The combination of the relay, constructed substantially as described,the sounderkey S, and rheostat It, when the Whole are connected and madeto operate substantially in the manner and for the purpose set forth.

3. In combination with the rheostat It', the double relay, when thelatter is so constructed as to effect the finer adjustments of theforces acting upon the armature or armatures, as set forth.

4. So arranging the several parts of the apparatus that the resistanceoffered to the current from the battery at either end of the line isalways the same, Whateverv may be the position of the key at theopposite end.

5. In combination with the key S, constructed as described, the rheostatIt', inserted between the key and the ground, substantially as and forthe purpose described.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

JOSEPH B. STEARNS.

Witnesses:

J. H. ADAMS, M. S. G. WILDE.

